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dakno · 18-09-2008, 15:02

If i buy a inverter, say2000w, connected to a battery bank, and plug a cruise-carry on type hatch AC, ..how do u calculate how long the ac would run before batteries become depeleted? How do u translate 12v amps to 115v amp hours. Figure the cruise/carry ac at 7 amps running load(115v).

Vasco · 18-09-2008, 15:11

about two minutes if you're lucky.

Of course it depends on the size of your battery bank. The draw from that a/c would be about 70 amps but I don't think a 2000w inverter will start the air conditioner.

S/V Illusion · 18-09-2008, 15:31

not going to happen (running A/C off an inverter).
Your cheap window A/C will cost you more in the short term - here's why:

Your 7 amp at 115VAC equates to approx 70 amps at 12VDC (obviously ten times the current). Startup will require higher current. That equates to a minimum of 800W but with power factor and inefficiencies, closer to 1000W so it's not the inverter which is the limiting factor but your battery bank.

Put another way, to run your A/C for 5 hours will require a battery bank of approx. 800 a/h MINIMUM.

You'd be spending more on batteries than the proper marine A/C unit...

AnchorageGuy · 18-09-2008, 16:07

I have never seen any inverter that will run any AC system for more than a couple of minutes even with any charging capabilities. It is totally inefficient.

hellosailor · 18-09-2008, 16:59

Danko, you'll need a generator (genset) to run the AC. Might not be able to fit in on a 27 boat. In order to run the AC overnight, you'd need a genset with a fuel tank large enough to keep it running 8-12 hours, and the small ones don't have that. (Refueling a hot genset is a good way to start a fire.)

The cheap gensets often made in china are for emergency use only--they won't last very long with regular use.

So...that AC is gonna cost you.